I see a srilankan problem here...
They guy must be on vacation and may not have cheated you..may be you are guessing things...
Check in MOI if the Visa exists (by visiting portal.moi.gov.qa ... select english at the top..select inquiries...Visa enquiries...Visa enquiry and printing....select passport and enter Passport number...Nationality..srilankan...verification code shown on the screen and press Submit.... then you should see his/ her visa.

If it is showing...you may get sponsor details by following Arabic version...

It is not a big deal to correct the visa for including the sur name..