Telkom new contract without consent

Telkom called me regarding on upgrade router from old adsl line rental system installed it and all of sudden have new contract that binds me although I was client for years and still pay bill on same landline rental numer and account. I newer asked for new contract to be installed was upgrade on existing contract at time. Have numerous problems with bill all of sudden also and is supposed to be fixed ammount but varoius every month and call centres can assist at all switch you from pillar to post without any problem resolved.