Virgin miles dilemma

I'm too cheap to have many air miles, and much too stupid to understand them, even though I've read the small print three or four times. When that didn't help, I emailed Virgin admitting its online explanation had challenged me and found me wanting.
Someone from [email protected] emailed back the very link to what I'd just said had defeated me ..... ho hum ..... PLUS (Thank You God!) a list of phone numbers, including one in the USA, where I'm on holiday.
I rang it yesterday, endured the recorded legalese preamble, only to be cut off before reaching any person.
When that happened for the third time I gave up, overpowered by a sensation that life is too short for miles .....
Yet all I'm seeking is the answer to what seems to me a simple question:
I've 11075 Virgin Miles pure and simple.
I believe my ticket class is N.
I'll be using the return half of my ticket from MIA to LHR on VS6 in May.
Do my Virgin Miles qualify me for an upgrade from Economy to Premium Economy on my return flight to LHR on VS6 in May?
(a) If yes, how and when do I request the upgrade?
(b) If no, how and when should I set about buying an upgrade, and how much is it likely to be?
Someone from [email protected] emailed back the very link to what I'd just said had defeated me ..... ho hum ..... PLUS (Thank You God!) a list of phone numbers, including one in the USA, where I'm on holiday.
I rang it yesterday, endured the recorded legalese preamble, only to be cut off before reaching any person.
When that happened for the third time I gave up, overpowered by a sensation that life is too short for miles .....
Yet all I'm seeking is the answer to what seems to me a simple question:
I've 11075 Virgin Miles pure and simple.
I believe my ticket class is N.
I'll be using the return half of my ticket from MIA to LHR on VS6 in May.
Do my Virgin Miles qualify me for an upgrade from Economy to Premium Economy on my return flight to LHR on VS6 in May?
(a) If yes, how and when do I request the upgrade?
(b) If no, how and when should I set about buying an upgrade, and how much is it likely to be?