Thorns, without knowing the details it's hard to say. Your account may be locked forever by their software for promos because of your betting or withdrawal behaviour.
However, I've become a bit of a master of this, that is my investigations running various scenarios with my nephew. Sometimes you won't receive promos because your not using them, but purely winning with the bookie.
What I have discovered so far is never use promos exclusively, never withdraw winnings and never leave money in your bookie account.
Withdraw by laying on Betfair and for bigger and bigger amounts.
A
recreational punter will fund his account, use his bonus and his funds and be penniless by the end with the bookie. He also won't bet the same amount on each bet. He'll use the "Moron System"
(Martingale) until the lot is gone. And won't put any more money in his account for at least a week.
A professional punter will put money in his account, leave it there or withdraw winnings after purely using bonus offers, he'll bet daily and usually for the same amount never his full bank.
My conclusions are purely from trial and error testing.
Thorns, I would suggest laying your win bets on Betfair and not solely using promos. It will cost you a percentage of your winnings, but you may be able to unlock your income stream after a while.