Black Listed for not using services

i took up a course with intec and paid a deposit, the sent me my study material, i never used any of there service or wrote any test or used any of their facilities, now they expect me to pay the full amount of the course, now they send me a message that a summons would be issued if i dont make payment by 31/01/18, this is ****************, how can i pay for a service i did not use and surely my deposit of 1700 would have covered the study material ...im sure they wont reply but this is so unprofessional i now have my name black listed and being threatened to pay for something i havent used. i have tried speaking to them on numerous occasions but they just send you from pillow to post....BAD SERVICE !!!!!! , Today i called intec only to be put through to NCRA debt collectors the lady says i have no choice but to pay and gave me the number for intec ********** 700 no one answers this number, she also goes on to say no one will be able to assist me as the account has been handed over . so in conclusion i have to just pay for something i never used. ...whats worse is that i cant even get a settlement amount.