I've never had a problem with either Royal Mail or ParcelForce.
I find DHL are the ones who tend to @rse about, especially with deliveries.
I bought a P Bass from Andertons, DHL brought it as far as Bristol,
where they let it sit at their depot for three days, then they returned it to Andertons.
I've just recently bought another P Bass, this time from Glasgow, again DHL,
it took them 9 days to get it here. I phoned them after 5 days and asked them if it was being delivered by pedal bike.