This letter doesn't work for me- you say things like 'I haven't done well', the tone is not formal enough. I'd do something like this:
I have been working in ABC hospital for six months as a general service assistant and I would like to move into a clerical position, a job that I would be able to discharge professionally and diligently, in TM hospital or CP hospital, as I live in TM.
Should you require any further information, please contact me.
Thanking you in advance, I look forward to hearing from you.
Student or Learner