What is interesting about your post is that you are given £12 for every £1 of annual pension.
Looking at the fsa website for pensions, for a 65 year old male buying a pension rising with the RPI, will cost around £24 for each £1 of annual pension. And a level pension (no increase over the life of the pension) will cost around £15 for each £1 of annual pension.
Based on the above numbers, it would appear to me that you are being short changed by your pension provider. I would assume your pension to be rising by RPI (possibly with other benefits) and therefore your notional pension pot of money which your pension provider should have (to provide your pension), should be around £24 for each £1 of annual pension. If they used this figure, you would be receiving £24 for every £1 of annual pension sacrificed, and not £12.
This smacks of another pension rip off – whereby your pension company can place a ridiculously low value on your pension, to minimise any lump sum payout to you.