how can i do this?

Quick facts
House price (accepted offer) £370k
Due to last minute hiccup my mortgage offer of £127k is now not enough, I recon I need at least £145k.
Any ideas?
I earn £28k the rest was a cash deposit
I wanted an interest only mortgage, do I have other options?
Equity release ?
Part repayment?
Until midday this was in the bag now I'm £20k short of my dream home
Gutted doesn't come close lol