Nerve Root Block Injection for nerve impingement

I'm worrying myself daily and wonder if anyone can help out there. Has anyone had a nerve root block injection for nerve impingement. I've had a dreadful year of health this year. I took on a new contract as a Medical Secretary in February and after a short time started to get pins and needles in my left hand. I finished the assignment at the end of March four days before I had a total knee replacement, which was successful. However after a month when I went off the 8 painkillers a day after the operation the pins and needles in my arm got much worse, and here I am in August still with them. I'm unable to continue to work, (I am 69 now anyway) as typing is painful and can't swim at all and this pain is with me all the day. Apparently the procedure is not always successful and can have some really bad outcomes, which I won't go into now. It should just block the pain although the nerve will still be trapped, but I'm not keen at the moment to go into surgery. The NHS can't do the procedure until the end of January, so I'm considering going privately, as I'm worried the nerve will get very damaged by then and I will have had the pins and needles then for 11 months! I've rung several times the NHS people who deal with this but no-one has returned my call, nor as yet have the private part of the same hospital. Can anyone tell me their experience of having this injection? I'd be really grateful.