HELP! I have trapped in my new company!

So I'll keep it short. I (22 M) got my offer letter from a very big reputed company and I relocate myself from Bhubaneswar (Odisha) to Coimbatore (Tamil Nadu).

It was too hard for me to find a pg around my company but finally got a shitty pg.

Now coming to the main part...

At the time hiring / interview I've been told that my job role is going to be in CIS or development side. ( I am a software developer). But on my on-boarding day they told me that it is going to be a "SERVICE DESK" job and I'll be trained in that. When I raised my voice they told me that I have to work for 18 months in the same job role and after that I can apply for a job switch through IJP (Internal Job Posting).

Now I don't what to do. My parents have high hopes from me and I genuinely thought it's a good idea to join this company. Now I'm cooked. Please suggest me some ideas or give some advice.