Complaint about MSA

Please assist ,i have cancelled with Msa on may 2019 as they were always late with my payments on my accounts ,so started to pay them directly by my self and its going good,my problem is Msa doesn't want to send me cancellation letter ,they keep on saying they will and they don't..... i have send them every document they needed from me for cancellation since May am still waiting....i need to clear the debt review status at Transunion as soon as possible ..please help me what can i do to get the cancellation letter.....