Here you can find some info and advice about courier services in the UK from my own experience.
Booking through middleman agent like InterParcel, ParcelMonkey or Parcel2Go could give you better price and most importantly – easy way to deal with any issues. Contacting couriers directly has proven to be a pain, while if booked through agent, you only have to deal with the agent. My preference is to InterParcel, as they are one of the easiest to get in touch with and are great in dealing with problems.
International shipping – if you’re sending your amplifier from overseas, usually easiest again is to use agent. InterParcel in particular has been tested to/from EU countries multiple times.
RoyalMail – usually good service for sending smaller parcels. If you’re sending in a Kube series amplifier module, that’s probably the best to use.
ParcelForce – good service most of the time. I’d advise to book using InterParcel as it makes it a lot easier to make a claim if needed. Prices are usually better compared to directly booking with them or in Post Office.
DX – works, no problems so far.
UPS – AVOID if possible. No easy way of changing delivery if needed, it’s very likely your parcel to be dropped off at a shop (UPS access point instead) which causes delays and parcel returns. If you insist on using UPS, make sure you advise them NOT to drop off at access points, where it can’t be collected from.
Collect+ – cost effective, no problems so far.
Hermes – used to be terrible service, seem to have improved a bit lately. Use if no other service is suitable. They mostly fail to collect and can be very slow to deliver.
UK Mail (iPost) – AVOID. Used to be working okay, but as it appears lately, the service has become one of the worst in UK and I have ever dealt with. They don’t reply to contact attempts, do not accept liability for damage claims at all! Currently acquired by DHL and trading as DHL Parcels, service hasn’t improved.
DHL – usually good service, but should you have a problem, it’s nearly impossible to chase them. They’d do everything possible to decline liability, even when evidence clearly shows otherwise!
Yodel – AVOID. Probably the courier with worst reputation in UK.