mis sold mortgage

over 3 months ago i got a letter from my bank saying that they have missold me a mortgage 5 years ago we took out a 10 year mortgage i had just turned 60 years old then , the lady at the bank said it would it would be best to take out a 5 year fixed rate mortgage which we did the payments was hi but she said that after the 5 years are over the rate should drop quite a lot in the letter they said i shouldnt have been given a mortgage after i was 65 years pld unless i was able to pay, they then said was i planning to retire at 65 or carry on working untill i paid it i told them that i was planning to retire at 65 because my payments would drop so i would be able to afford it , they asked me to give them 8 weeks to investigate after the 8 weeks was up they asked for a further 4 weeks now that time has lapsedthey want more time i dont know what to do now .