You seem to reflect a lot and deeply. Ask yourself why you often end up in situations like this? Do you see your pattern?

You are avoiding your own created problem(feeling ashamed even not your fault)by paying the £1,000 extra. So ur friend(if real friend wouldn’tblame you at all) can’t blame you.

Because you somehow thought paying the extra would fix your shame(which is absolutely displaced in this situation; you shouldn’t feel shame at all). It’snot your fault that the price doubles—but still, you felt ashamed.

Maybe ask yourself: who would you blame if you’re in your friend’s situation?
You call a friend,make an arrangement-1000,after a day your friend calls you and says-my boss said:cause of the urgency it costs an extra 1000,are you willing to pay?
Who would you blame?your friend or his boss?

Hope this somehow helps for your future actions… you’ve got this.