I am being illegally evicted and I dont know what I can do about it.

When I split up with my ex a few months back, we agreed that I would rent his flat from him.  It was only a verbal agreement, and nothing was put in writing, but I paid him rent through a standing order, and everything was fine.  However, I went away on holiday over christmas and new year, and ex obviously turned sour, as I have been informed that I am not to return to the property, and that the locks have been changed, and that they have arranged for a van to pick up all my stuff in the property so that I do not go near it.

My understanding of it is that I am still a tenant even if there is no written tenancy agreement, and that what he is doing is an illegal eviction. The problem is that I don't know what I can do about it: how can I get back into the property on my return tomorrow night?

Thank you for any advice you can give.

thanks, will do