CELLC - MBD Debt Collectors

Hello, my partner, Verina Kilian and I, Lawrence Pearce cancelled our CELLC Contracts, within the prescribed timelines, terms and conditions, as we do not want to re-new as we are going overseas, and requested to keep our numbers, just move onto Pay-As-You-Go. According to CELLC, our contracts have been cancelled, and we have been moved onto Pay-As-You-Go, as requested. Due to CELLC's inefficiency, we have now been handed over to MBD Debt Collectors, for money owed, after all contractual obligations from our side have been settled? They are requesting all personal details, before they even talk to us, but they have all this detail already. We have attempted to call and email CELLC to resolve, have even asked for Proof of Contracts, which they cannot supply. We just cannot talk to anybody with any understanding or sense. Everything is in writing, for which we have proof of all correspondence. CELLC sales is also calling to offer us new special contracts - how can they want to renew our contracts if we owe them money according to them? Now we assume the Debt Collectors are charging us for every call, which they usually cut short or terminate on greeting, and accruing interest and ridiculous amounts to be collected, and have black-listed us, which is totally unacceptable. We would like this resolved, and clear our names, as we have never owed anybody money that we have not settled. Thank you for your professional assistance. Regards, Lawrence & Verina