Help out little girl Lottie

This is Lottie, my nans girl.
A few months ago she got a small lump on her head, it was squishy and small but started to grow.
She was taken to the vets the other day for a check and a biopsy which has cost well over £500 just for that.
Now my nan and grandad are both disabled and can't afford the £624.66 the vets want to remove it.
The biopsy came back and luckily it's not cancerous but a rare tumor which will continue growing my nan got the call today about the price and vets she's spoken to have all said to have it removed though it's not cancerous even malignant tumors can grow cancerous if left untreated like this one.
Please if anyone can help they would really appreciate it ☺️