What to do if avios upgrade becomes available whilst abroad on ba holiday booking
 

Unable to upgrade via mmb as I have a holiday booking with ba, tells me to ring an 0844 number but I am already at my destination in the USA. No availability on my return flight so far but if two upgrades in club appear I would like to grab them, managed to do on outbound flight.

Use your internet connection to check for availability with a dummy booking and then call the BAEC US number to process the upgrade if availability opens up. It's a toll free number or you could use Skype to call it from a mobile device or laptop.

As above - Skype to the toll free number works.

www.saynoto0870.com should also find you a low-cost alternative to the 0844 number that you should be able to Skype to.

BA should now also be publishing 0191 numbers.

Having just done this, ensure you do not get off the line until your ticket has been reissued. I revised my booking on Saturday for a departure tues. Saw all was well in MMB and no sign of trouble til check-in. Spent an hour personally on the phone with the exec club customer service folks until it was 1 min til check-n closed. The desk agents have no recourse for a botched ticket...ymmv. (This was at LHR First checkin at T5 fwwiw)

BA Holidays (the specifically branded products they sell) actually have a 24 hour helpline, the number you will find buried in your "non flight vouchers" attached to the relevant email. You will also find this number, shown as the "in resort" helpline if you go to Manage My Booking, select the Hotel line, Print Non Flight Voucher (you don't actually need to print it, it comes up on screen) and it's two thirds of the way down. It's an 0208 outer London number. Ditto for Car Hire based bookings.