Refuse to repair phone

On the 18 June 2015 we handed in a blackberry 9790 in for repair. The phone is still within the two year guarantee. The job number was ***9. The phone was returned to us on the 24th June and we were told the rpair was guaranteed for 3 months on the repairs. On the 10th we took the phone back for the same faults with the job number ***9 and today I was informed that I need to pay for the repairs. The amount is almost the same as the value of the phone. I am requesting that you abide by the guarantee on the phone. when the lady called me to inform me of the amount I explained the situation she promissed to call me back in a few minutes. She called me from *** at 0914. It is now 18:35 and nobody has called me back. This is unacceptable customer service.