Getbucks/ MBDCS get your **** together!!

My account was in arrears, I called Getbucks/ MBDCS to settle an account 2 weeks ago. I paid up the account on the 5th of April 2019 and sent proof of payment as requested to ********** that's when the harassment began. I receive calls daily from MBDCS and everytime I send them the proof of payment but the calls don't stop. When you call their call centre no one picks up, I went as far as calling Getbucks and they tell me they've received the payment and even sent me a paid up letter but MBDCS is still harassing me. Can MBDCS get their **** together before calling, I've sent them FIVE proof of payments already. The next person that calls me telling me I owe Getbucks will regret it.