Application to reposses a vehicle . Scotland

[Brown999]

My son received a citation from the sheriff office, the finance company have made an applcation to re possess his vehicle or pay the full amount outstanding. they have stated that the agreement was terminated in May 2018. He was at that time in arrears, i complained to executive office and they agreed arrears to be paid in full to stop action. this was done and the normal monthly instalements have been made since then. out of the blue this order arrived saying they will reposess the vehicle. They are still accepting the monthly instalments at present. my question is if they are accepting payments have they lost the right to repossess.? sorry for long post.