[EmmaL4]

I am trying to book my returns from Tokyo to Heathrow having booked my outgoing with my 2-4-1 voucher. I don’t have enough Avios to book 2 tickets and then get half returned. I have seen on here that there are mixed results from calling the US number (which is actually based in the UK!) so I rang the UK number to find out what was the best thing to do. I spoke with a very nice man who said they weren’t supposed to advise calling US number but wouldn’t tell me not to but he also suggested that I book using less Avios and more cash and then calling the UK office and they would link the booking to my outgoing, take the correct amount of Avios and refund the cash. He said it was definitely possible to do this. Having read into it, I didn’t see anyone suggesting this so I called the office again spoke to a different agent who gave me completely different advice. He said I couldn’t do this and suggested ringing the US office which is infact exactly the same office as the UK, just on a different shift!!
Has anyone tried using less Avios and some cash and then getting it refunded later when it is linked to voucher booking?
Also, do you need to put 00 in front of the 1 for the US number and the 03 for the Japan number?