Tesco direct buy one get one free?

Ok, this will take me a few minutes to explain this whole situation. So on Sunday i purchased 2 bikes for my children for christmas, paid for them, recieved an email the next day to inform on delivery. Brilliant! Until I recieved an email saying the bike for my little girl was out of stock and they had refunded the money, i was livid but not as livid as I was as this story unfolded. I called tesco direct frustrated that I their website had allowed me to purchase an item that was no longer in stock, so I suggested to them that I would purchase another bike from them for the same price as the original. The man i spoke to spoke to his team leader and they agreed they would do this. He explained that to put the refund through he needed to speak to the card services department and they were very busy so he would call back within the hour.
4 and a half hours later i still hadnt recieved that call, so i called them back. I grew increasingly frustrated because it took me 40 minutes to get through to anyone, then the lady i spoke to was so accomodating, she arranged the refund and explained i would have to be charged the full amount and then they would refund my account. This was fine as I had recieved a refund from them before after being charged twice for something, but thats another story. Anyway the purchase was made and i recieved an email with confirmation of delivery.
The next day the bike arrived, but not one.....two! So again i checked by bank and still only one has been deducted from my account? This has been 5 days now since delivery but i noticed on the invoice sent it had a gift card on there for -£125.95?
I called them to notify them that i now had 2 bikes as i wanted to be honest, and they have told me just to keep the second bike for all the hassle i recieved with my order as a goodwill gesture. Thanks tesco