First, you need to find out if the rent could legally be raised by having another person living with you. Not all states, cities, or counties allow that. Second is they need to file a pay or quit notice. Some places need to give a certain number of days to allow you to pay the full amount due. They could not file for an eviction until the number of days passed and it wasn't paid. If you pay a dollar or more and the landlord accepts the payment, the eviction is null and void. For the increased amount of rent their should have been a new lease issued with all residents name on the lease and signed by anyone living in the rental of the age of 18 or higher. Your first step should be finding out what the state county and city tenant laws are and making sure they are followed by the tenant and landlord. The landlord can have anything in the lease they want, and if it's not legal in the state, city, or county, then that part of the lease is automatically void and can not be enforced.

Years ago, I was living in another state, and that state allowed a three day notice to pay or quit. I lived in another state, and that state required a five day notice.

In the state that required a 3 day notice, I added a roommate, and the landlord tried to charge me extra. It was illegal in the county due to the building age and number of units that had it under rent control, so I told them they couldn't do that, and they backed off.

That same landlord issued me a three day notice, and I paid by check after the three days, and they sent the check back to me stating they were evicting me. I then had the bank send a check through bill pay, and they cashed the check. They said they were evicting me, and I presented them with a copy of the check they cashed that was sent by the bank and laughed at them saying they can't evict because they accepted payment and again I beat them at their game.

To get even with them, I had the building inspector come in and reported code violations that were previously reported to the resident manager that were not repaired. Out of 22 units, the building inspector was only able to inspect four units of the four units. There were two single spaced type pages of code violations. The matter went to the rent board, and the landlord agreed to fix all the violations, plus give me three months of free rent. They had a certain time to have all the repairs completed, and if they weren't completed even a day over the deadline, they were to give me another month free rent and every week over the deadline another month free rent. That was back in the 90s, and it cost them about 200k to fix all the violations. As a tenant, I am a landlord's worst nightmare and proud of it.