Hi @Lexie,
edit to the above, the 350 you have already received is advance GCB for your CURRENT car. Upon returning it you should get another 250 (assuming a 3 year lease) i.e. 600 in total. You will then receive your additional 250 new car payment.
Assuming that you ordered your new car before 1st October you will receive another 35o after taking delivery, and then a further 250 GCP at the end of your 3 year lease.
I said it was confusing! lol
Sean
Current car Hyundai Kona Ultimate EV