Fully paid my account but now am getting email from collections company

I have been with wonga for a while but haven’t been taking any financial services for the past three to four months . I have recently received an email from HTN Attorneys advising that mg account has been handed over to them for collections purposes. I call customer care and was advised my account is not in arrears , I tell call the attorneys company and was provided with the statement and advising to enquire with wonga . I forwarded that’s statements to za.customercare@wonga .com and called the immediate . I spoke to a lady that said she can’t see the statement I need to call Htn and advise them to send it via pdf ....poor customer service why does this have to be my problem , why can’t they call their partnerships and request for more info . Then request to speak to a manager , I held for more than 5 min with no one came back to me and had to release the call , thus far no one has gotten back to me

What frustrates me the most is that I never had any failed debit order nor account disputes with them

This is ruining my credit record ?