Dispute with Pt

ST12

Hi I’m new to the site and after some advise. I purchased a personal training package in may which consisted of 12 sessions. I then went into purchase a further package again 12 sessions. It was agreed between me and the personal trainer that that I would have 2 sessions per week which were booked in advance. I had no issue with the personal training it’s self I did however have an issue with cancellations. The PT cancelled on 8 occasions ( all sessions were always rebooked back in). After the 8th cancellation I had had enough and at that point asked for my money back for the 3 sessions I had left. This was agreed with the PT and she gave me a date when she would refund. This date came and I received a message saying she had had some unexpected business costs and was unable to pay - would I take the 3 personal training sessions instead. I wasn’t happy to this and wanted my money back, I did offer to wait another month for my refund which the PT agreed to stating they would pay 1 amount the next day and the 2 remaining amounts at the end of the month. The Pt then withdrew this offer and stated basically I had to take the sessions. So far I’ve spoke with citizens advise who advised I write to the Pt. I have done this using the CRA 2015 as I feel she failed to provide the service with reasonable care and skill - due to multiple cancellations ( the pt is now trying to say it was rearranging of sessions), and have again asked for my money back for the 3 sessions I haven’t had yet. I received a 6 line txt the next day saying I signed a contract and my consumer rights are non negotiable????. I simply want my money back for the 3 remaining sessions and feel this is my right to do so. Citizens advise have now said I could send a letter before action, just wondered if anyone had any advise for me re: this issue, many thanks