Whether they are loathe to adminster the benefit or not, they have no right to force you to transfer.
To be honest, I'm not sure what your rights are in terms of the payment. Were you perhaps looking for it to be paid annually for example? I've seen this happen in the past, but I dont know whether you have the right to demand it.
You might have some options in relation to the pension though, but you'll really need to check out your booklet or Trust rules. For example, usually you'll be allowed to exchange up to 25% for a tax-free cash lump sum, so might be worth considering depending on what conversation rates they offer you.
They could secure your benefit for you with an insurance company, but it would need to be the full £500 pa regardless of how much the insurance company wants for that annuity. If they just pay you a transfer value, you'd need to find somewhere to take it yourself (and I'm fairly confident a standard transfer value wouldnt buy you a £500 pension, although they might look to offer you an enhanced value to encourage you to tranfer).
The old trivial commutation rules used to look at just the pension scheme in question, but the limit for that was only £260pa so you wouldnt have qualified to take the lump sum then either. I believe they are looking at changing the rules again, but I dont know when or if that will actually happen.