The issue you face is that not many local dealers will want to touch an ebike so old, or one they didn't sell. The best option, if you can, is take it back to the dealer you bought it from.
If you just want the part, Ebco themselves may have some left-over parts, Holland Bike Shop sell or can source a lot of TranzX parts, or ebay - you often see old Eagles broken down and sold as parts there, or else complete, cheap working and non-working bikes for parts. There's a complete Eagle today, apparently working but needing a new battery, currently bidding at £90.
If you expand on what you think is wrong, other technical folk here may be able to advise on where the issue may be.