Handed Over for Debt which doesnt exist

This morning I received an sms from NuDebt, saying we owed R1800 on our business Telkom Account. We checked our account and its up to date in terms of payments, then decided to visit the Telkom Office in N1City. There they loaded the query online and a consultant called us as they only "do sales". The consultant confirmed that they had definitely not handed us over, there is no arrears on the account. They put me though to various departments, billing, sales, customer services, each asking the same questions and at the end of it all, confirmed we are not in arrears. So I message NuDebt and advise same, the response I get is, its for services rendered by Telkom and please advise when you will pay R1802???? now what the hell. We are a small business, in the process of applying for funding, we dont need derogatory information linked to our business, especially now. So how do we solve this. If you didnt hand the account over to this company for services you apparently rendered to us without any proof sent to us, what do we do?