Bladder Spasm after SPC insertion?

My friend has paralysis after a traumatic incident and it was decided that it was best to have a Supra Pubic Catheter placed so that after 7 months she could be released from hospital. My friend now has very painful bladder spasms throughout the day which breaks through strong pain relief. She has been told three different things by three different doctors from infection (antibiotics administered with no effect) that it is 'normal' to 'it will get better'. It is now 4 months since the catheter was placed. We would hope that we are able to keep the catheter as it makes caring for her so much easier but the pain has extreme bursts and it is becoming mentally draining for the patient. Has anyone else had this problem or can suggest something to try?