oustanding balance

I cancelled my contract, got confirmation that I do not have any outstanding fees in 2020 and then years later ie 2024 , without any communication from Supersonic I get an SMS from a debt collections company stating that I have been handed over. I asked for proof from Supersonic for proof of communication that they have informed me of this outstanding fee but nobody is able to supply this! ive been waiting online for 45min yet no answer, i sent a message on the Whatsapp number, no reply