Unfortunately for you there is no cap on rental increases for residential property. There was one a few years back but the law was only for a few years and was never extended.

I guess you could try to beg and plead with the landlord not to increase it, but he is legally entitled to do so.

Another idea would be to start looking for a new place to live if you can't afford the rent.

Finding affordable accommodation in Doha is a problem for everyone these days.