Wrong billing

An agent called me in February for a Samsung A25 deal which amounted to around R270 and I accepted.The phone was couriered to me & I received it then 3 days after telkom sent me another phone which was the same as the one I already received but I didn't take it from the courier I immediately called telkom to inform them about this & the agent on the call advised not return it with the courier as I did.From the end of February I am being billed for 2 phones & I've been calling telkom sales about this matter they say that unfortunately I have to keep on paying for both phones until they find the other one.My question is surely if I accepted the second phone I would have signed the waybill & why dont they check with the courier about that package.I regret ever taking that deal,telkom is the worst ever unprofessional company.I can not keep on paying for someththat I dont have.