We ordered a Burley Solo from them 2 weeks ago – got excellent service, but was horribly let down by Royal Mail – they 'forgot' to put the parcel on the van so it sat in their main depot for a day (after paying for before 10am next day guaranteed delivery) – I contacted CRC by phone, after 4 attempts of the engaged tone, I got through – so about 10 minutes trying) – guy was very helpful (and apologetic), refunded the postage and sorted what he could at his end (admittedly he couldn't get the parcel from the Swindon depot to the house any quicker but he did do the refund immediately.
I then discovered the next day (after leaving holiday at 5am to get home for 7am as I was told the driver could be there from 7am), that Royal Mail don't do a guaranteed before 10am next day service in my area but it would be there by 12.
CRC's system didn't check this part of the postal system (not sure it could)…that would be the only criticism I'd offer on this experience, CRC did everything they could as quickly as they could, but Royal Mail let the whole thing down (the driver turned up at 11:56 – dropped the parcel on the doorstep and asked me to sign before scurrying away).
I'd keep trying the phone…as much as it is engaged it will free up eventually.