Issues with My Fitness Pal not connecting and errors occurring

I recently got a free subscription of three months to My Fitness Pal because I have a Fitbit watch and wished to have the data transfer to the app. It worked for a while but when it stopped transferring data and I was receiving other errors, I cancelled the free trial and then requested the full programme. The issues remain and I wish to get a refund for what I have paid for the whole year due November 2023. I contacted My Fitness Pal organisation and they said I need to contact Apple to sort this problem out for me. Can you please help?