My Employer wouldn`t provide me with a letter stating my duties.

From many comments so far on intra-company transfer, it seems the employer does not provide duties which doesn't make any sense. You are obviously showing up to work and doing something, the least they can do is provide you with a list.

In your situation, I would consider doing the following:

1. see if there is anyone else in the company who would be willing to provide this to you

2. ask your hiring manager/department for a copy of the job application you submitted for the position - your resume/CV will likely contain duties which were a match for the employer

3. ask if you can obtain a copy of the original job opening you applied for - it should have main duties

4. look at your job offer/contract - does it have this information?

5. check the employer's website to see if there are job openings with the same title and duties as yours - get a copy

Make sure you request this information using email so that you can have evidence of the efforts you made to obtain the information and the employer's response. If all else fails, provide your resume with all the duties you performed in the position along with evidence of your efforts. Also include contact information for someone who can confirm your employment.