upvc back door and frame (Osbaston TF6)

I am in desperate need of a new back door. I am in the process of bringing our house up to scratch. Due to very poor health for what seems like forever my house has fell in to a bit of disrepair. My front door locked seized up and stopped working a while ago, so have been using the back door only. Now, to add insult to injury that has died as well. The door got accidentally locked while it was open and just to make my situation even worse, the lock on that do stopped working. When you turn the key it just spins. Anyway, I am currently stuck in a very bad position and am in no way shape or form financially able to buy a new or used door. I really need help!!!