Companion voucher - applying against existing booking

Watching MCO-LGW like a hawk for PE flights, if flights come up for me and my wife can I book these instantly and then call up and have them apply the companion voucher and in turn return me the difference in points?

Yes, we have had the voucher applied to existing bookings in the past. Just give them a call.

That's great thanks..

Thanks for posting the question as it encouraged me to enquire if we could award our two credit card reward vouchers against our PE ( paid with miles) seats. Booked over 10 months ago We only had one voucher at that time. We are currently in Puebla, Mexico flying back via MCO to MAN in 4 weeks. The only downside is it had to be done by phone or txt. ( I don't have a phone contract for free worldwide txts)
The first response was it couldn't be done, but I asked them to make sure that is correct, although I was clear that it wasn't a big deal if the answer still came back “no “ and thanked them in advance for their time in finding out. Then the answer came back “yes” and they just needed some details.
My husband was mildly amused at my grimaces every time I received texts followed by more to complete the transaction, then once it was all finalised another one asking me to review my experience during the process.
Having been refunded 20,000 miles at no cost to us which would have cost £300 to buy, a future mobile phone bill of about £10 Just for txts is still a bargain.
I was wondering if I had the Virgin App would that have been a possible avenue, as wifi has been widely available whilst away, Mexico City in particular having city-wide free wifi.