Andrews letting agent issues

HI all, sorry in advance for the long post!

I was wondering if anyone has had any issues with the Andrew's letting agents in town? My flatmate and I seem to find ourselves in a very frustrating situation with them and I was wondering if anyone had any advice.

I share a property with my friend currently, but have decided to leave the property and move in with my boyfriend.

In my property contract, it says I had to give a month's notice i.e. 4 weeks. Our tenancy renewal (or moving from fixed element to periodic element after 12 months) is on the 21st of August 2024. I gave Andrews more than a month's notice (11th July 2024) stating that I would be moving out, and if a tenancy swap would be possible. I also notified our landlords on the same date that I would be moving out and that my flatmate wished to remain.

We then proceeded to hear nothing back until the following week, when we were advised that our letting agent was on annual leave, and they had to check that the landlords would be happy for a tenancy swap to occur. We then got confirmation on 29th(!) July that a tenancy swap would be acceptable and that we had to let them know of the details of the incoming tenant by the 8th of August at the latest date.

We provided the information of the incoming tenant by the date they told us, didn't hear anything back again for 5 days, and have now been told that they won't be able to complete the paperwork in time, so I will have to remain on the tenancy until 22nd September as it needs to be completed around the date the rent payment is due, etc.

They have given us a couple of excuses such as; August/September is our busy periods for students moving in and out, we have had two staff leave, and our letting agent is on annual leave again so there was no one to deal with it (even though we e-mailed multiple people at Andrews without a response) etc but in all honesty this is even more infuriating because it means that I am now apparently liable for rent etc even though I won't be living there.

Has anyone got any sound advice as to what I can do? I feel that this is completely unfair as I gave them more than adequate notice, and then they turned around and said they didn't have enough time to do the paperwork because they gave us the incorrect timeframes for everything.

I'm at a loss for what to say or do, as they have just said to me today that I have 'taken a risk' by agreeing to a tenancy at a different residence when I wasn't out of this one yet. I signed the tenancy agreement after they had said that the landlords had accepted a tenancy swap.

Thanks :)