What model is your PS3?
If its a 3000 series you cant downgrade anyway. (probably isnt though after you said you fixed it ylod?)
£106 seems a bit steep, but if needs must...
You will also need a FSM dongle to downgrade, and double check your console even CAN downgrade to 3.55 by using MINVERCHECK in my sig below.
Best guide around: http://www.ps3hax.net/showthread.php?t=33989