Just a quick question:

1. Is it possible to change a Miles-only booking to Cash & Miles?
2. If so, does the ticket need to be reissued?
3. If the ticket is re-issued, and the taxes recalculated, what happens if:

- The total taxes is lower than when originally booked (say, from £200 to £100 thanks to reduction of YQ)
- The "cash" portion of the M&C is added to the lower tax (say, £170)

Do you pay the original taxes + cash portion, therefore the entire "cash" portion (£170), or
new taxes + cash portion - original payment (£100 + 170 - 200 = 50)?

Thank you!

PS. I omitted the change fee from the above to make calculations simple.