out standing balance after final settlement ?

electrician1

3 months ago i remortgaged to a lot better and cheaper company saving me £400 plus as i paid my normal payment to spml (capstone) on the friday before my new lenders completed on the following wednesday after all the legal eg solicitors,valuers etc had done there stuff and all parties the results of the property value and final settlement figures.

capstone(spml) refunded my over payment with in a week.

but five to six weeks later i was told there was a £600 charge on my house by the solicitor and spml due to a missed payment 3 years ago and i must pay this money to release the charge i have spoke to spml and asked them to send statement showing this but have not had a reply after they said they would.

what is a final settlement figure any advice