How to Change my Profession In Iqama

Please tell me about This:

- My profession in Iqama is 'Mason', is it Changeable ?

- I have BSC(Computer Science) Degree Attested from HEC, MOFA In home Country.

- When i went to Saudi Embassy in My Country for attestation of degree , they asked me about JOB OFFER LETTER from company in which i am working. I have Letter now attested from Chamber of Commerce , but Not from Ministry of Foreign  affairs Saudi Arabia, Because when i went to MOFA in Riyadh for attestation they refused.

- I have good Job Offer , But Company said that my Profession 'Mason' is Not Changeable .

Please tell me how to change ?

Thanks