i hope the chips i sold you are not in the same state as the ecu you are changeing
try vauxhall performance spares centre in walton on the nase essex, they normally have them in stock
expect to pay 100-120 for ecu and likewise for the loom, if it is a loom problem you have i would consider buying a gwr motorsport loom as the loom you will be buying second hand is like 10 years old and share the same problems and faults
the upgraded loom is much more expensive but it wont go wrong and blow an ecu up resulting in more expence
whilst upgradeing to phase 3.5 i have been useing a standard ecu from wallace performance...as i have chip problems myself.
gavin might be intrested in selling his standard ecu, it might be worth a call