New employer not giving me contracted hours

Hello! This is my first post on Money Saving Expert, and I'm afraid it's going to be a long one. If anyone can help me it would be greatly appreciated. Buckle up, folks - it's story time.

I applied for a job as a receptionist in a hotel. I was given an interview with the deputy general manager, and a few days later he got back to me via email. He said that he was impressed with me, but that he'd found someone with more reception experience and was going to give them the job. However, he offered me a housekeeping position (since I have experience in housekeeping) and said that I could be trained up for reception once I had settled in. Before I accepted, I emailed back asking about the contracted hours. In his reply, the deputy GM said that it was a 40 hour contract, and I accepted.

On Monday (15/01/18), I went into the hotel to sign my contract. The general manager had written '30 hours' on it. I challenged him and he said that it was officially a 30 hour contract but that it would be "more like 40", which is why he advertised it as a 40 hour contract. Yesterday I started my first shift at 9am, and the housekeeping supervisor told me some things that were quite worrying. She said that the housekeepers often finished early and were sent home without being paid for the rest of the day. She gave me an example, and said that one day last week, the hotel was extremely quiet. All the rooms were clean by 1pm, and the housekeepers were sent home - after only working and being paid for four hours.

I emailed the deputy GM in my lunch break about me agreeing to work 40 hours a week - so, eight hours a day, five days a week. He replied saying that he put me on a 30 hour contract "if I remember", and to take into consideration that because I was working as an extra while I was training, I could expect to finish earlier.

At 3.30pm, all the rooms in the hotel were clean and the other housekeepers were sent home. I was asked to leave as well, but refused, explained the situation, and said that I would leave at 5pm. I helped a porter with a large linen delivery and then the general manager realised that the whole hotel could do with being hoovered, so she let me do that. Before I left at 5pm, the housekeeping supervisor told me to come in at 10am today (17/01/18) rather than 9am. I asked why and her answer was very sketchy and to be honest I still don't understand. So, I accepted that I would be working seven hours today and went into work at 10am.

Today, all of the rooms were clean by 2.40pm, and the other housekeepers were sent home. I was not asked to go home, and was instead asked to clean and organise the hotel's three linen cupboards. I cleaned two of them and at four o'clock I asked the general manager where the third cupboard was as I still hadn't completely found my way around the hotel. She informed me that she and the housekeeping supervisor had already cleaned it "so we could finish at four". I was furious - I had only worked and been paid for six hours.

I'm hoping it will get better once I start my reception training. I know for a fact that the receptionists work eight hours a day, guaranteed. But I can't keep doing this for two months. The general manager tried to cover her back by saying "sometimes you go home early but other days we might need you to stay late so that makes up for it" - but there's no way they could guarantee that some days I'd need to stay late. I've been keeping a log of my hours, including the times all the work was supposedly finished, the tasks that I completed after this statement had been made, and the times I went home at. Tomorrow I'm going to ask for a copy of the contract that I signed to see if there are any loopholes that the management are using to their advantage.

So I suppose what I'm asking is - am I in the right or the wrong? I feel like a mug for believing the deputy GM when he said that it would be "more like 40" even though he had written down 30 on the contract. Is there anything I can do about this? I really want stable hours with stable pay. Any ideas?

Thank you,
Rachel