It does not seem correct to me. Whether you are a new or old customer it does not mean their rates will change - very odd.

Perhaps try and get someone to act as though they are a new customer. I reckon they would shoot the price up when it came to the booking, there is no way on this planet that the price they would get would be that cheaper if they were to book a new customer as opposed to repeat..

L

I might have it wrong but my reading of the OP is that they booked a holiday for September 2018, then saw details of this offer for halfterm in October 2018 and now wants to cancel the September holiday so they take advantage of this offer? Hence the cancellation/admin fees? It's standard practice to limit such offers to new bookings rather than them being applied retrospectively to existing bookings.

As I understand it the OP could take advantage of this offer if they booked it in addition to their existing holiday ie went away as planned in September and then again in October but the TO has said that they can't just swap their bookings and go away in October at the cheaper price instead of September.

SM

I agree with SMa. They have an existing booking but want to avail themselves of an offer than wasn't in existence at the time they booked so would have to pay any and all relevant fees. Offers aren't retrospective. They're always new bookings only.