Help! I have had problems with no /lose power when driving at 30 MPH. on 2006 Honda Civic

When driving about town I have an intermittent fault that suddenly I get little or no power when pressing accelerator. This has been like this for 2 weeks, and then yesterday engine warning light came on. Garage have said its the glow plug, and relay, up to now its going to cost £319. Has anyone had this problem with their Civic.

Asked by for the 2006 Honda Civic