'G' class availablity nearer travel date

Evening ladies and gents.
A couple of weeks ago I booked economy return, LHR-SFO through a Thomas Cook branch. Normally I wouldn't touch TC with a barge pole, however I had a large amount of vouchers through a work incentive scheme I wanted to use up.
I booked a 'Q' class fare 27/07/06 rtg 31/07/06 (for the marathon). £737.40. (ouch)
A week later I thought, the day after the marathon, I'm not going to be in great shape, let's see if I can pay the upgrade fee to 'L' and then use 30k miles to upper. (I.e. just the return leg)
I rang FC, they said I needed to get TC to upgrade it to 'L', then ring FC back to upgrade to 'G'. They said there was only one 'G' seat left.
So I ring TC. They fob me off and say they will ring me the next day. To cut a long story short, they managed to spend three days not doing what I asked, and each time claimed they couldn't get through to VS's travel agent department ("we were on hold for three hours" = sure you were!). Eventually I gave up and rang VS to see if they could sort it out, by which time the 'G' had gone. Hence me being livid with TC (complaint letter already sent).
So I have to face the thought of sitting in Y the day after the marathon.
Well, FC said once I've flown on the ticket (i.e. arrived in SFO), I can then ring them to upgrade the return leg as 'G' availablity may open up.
Does this happen much - do you think it's likely? Given it's a busy time of year, etc.
Cheers
Andy
A couple of weeks ago I booked economy return, LHR-SFO through a Thomas Cook branch. Normally I wouldn't touch TC with a barge pole, however I had a large amount of vouchers through a work incentive scheme I wanted to use up.
I booked a 'Q' class fare 27/07/06 rtg 31/07/06 (for the marathon). £737.40. (ouch)
A week later I thought, the day after the marathon, I'm not going to be in great shape, let's see if I can pay the upgrade fee to 'L' and then use 30k miles to upper. (I.e. just the return leg)
I rang FC, they said I needed to get TC to upgrade it to 'L', then ring FC back to upgrade to 'G'. They said there was only one 'G' seat left.
So I ring TC. They fob me off and say they will ring me the next day. To cut a long story short, they managed to spend three days not doing what I asked, and each time claimed they couldn't get through to VS's travel agent department ("we were on hold for three hours" = sure you were!). Eventually I gave up and rang VS to see if they could sort it out, by which time the 'G' had gone. Hence me being livid with TC (complaint letter already sent).
So I have to face the thought of sitting in Y the day after the marathon.
Well, FC said once I've flown on the ticket (i.e. arrived in SFO), I can then ring them to upgrade the return leg as 'G' availablity may open up.
Does this happen much - do you think it's likely? Given it's a busy time of year, etc.
Cheers
Andy