No guarantee for a job not done properly

Came in to unblock a toilet. Managed to clear it but did some digging. When we received the invoice it says that they won't guarantee the work because of the condition of the pipe but we were not told that there was a problem with the pipe at the time of the job other than that it is difficult to get to. R1400 ex VAT 2 weeks later we are back in the same position. I was told that facial wipes had blocked the pipe, well nothing other than toilet paper has been put in the toilet since. When you aren't told that there won't be a guarantee how do you decide whether you want a job done or not. I would have called in someone competent enough to do the job and guarantee it