Why was I handed over to two debt collectors at the same time?

I had a laptop contract with them, due to financial strain I was unable to meet my monthly payments therefore I was handed over to debt collectors, but why do finchoice had me over to two debt collectors at the same time? So I paid and settled my account but Nimble group has been harassing me and I have to explain myself over and over all the time, at the same time I have paid a certain amount to them and it's been over 3months without getting my refund, how long does it takes to see on your system that the account has been settled, now I have to be busy chasing your debt collectors? No this is unacceptable!!