Your regular contributions are buying units most likely in a fund, obviously the reason why your total value has gone down is due to market conditions world wide, however you are still buying units. When the market bounces back it will happen very quickly and then price you are paying for units at the moment in a depressed market will give you a significant gain as you are buying units at low prices.
If you transferred the assets into something more secure now, basically you take the hit, its like negative equity on a house. However if you wait, then if but more likely when markets recover you will be in a better position.
If you remember the same thing occured with SSIA's, people who invested in equities were down half way through but by the end of the 5 years they were in a better position.
You need to ask yourself some questions in my opinion
1) What age you wish to retire, if its 60 then you are right to be concerned as 3 years is not a long time for markets to recover, if its 65 then there is more chance.
2) If you are a higher rate tax payer or even a lower rate tax payer, is the tax relief outweighing the loses incurred by the fund, if it is then technically you are still up and have the chance that markets will bounce back to further increase your fund.
3) Is your fund automatically going to move your fund into safer assets, this is good in good times but not necessarily good at the moment.
I hope this reduces some of your concerns but you should give a financial advisor in the bank you have your pension with if you need further reassurance as they will know exactly what type of pension you have.
Regards
Stephen