HDC Fault

Dear Members.
I bought a used RR Sport (2005) about a week ago. It is my dream car. Go a loan to buy it in fact!
However, I keep having the following problem: Start driving, everything is ok, then I get these yellow indicators and HDC faults, special programs inactive, etc and the car cannot be lowered or hightened.
Took it to the official service where they changed the alternator 3 days ago (bless the guarantee for that!). Happy as I was, I drove the car the following day and the same problem reappears.
Really frustrating when it is the car of your dreams and keeps causing you a headache! Any suggestions please? Much appreciated!!!

Also changed the battery today. Entirely new fitted, still same problem...

Amazingly, I noticed the HDC light + special programms not available turn on after I do a distance of about 8-10 miles... Isn't that weird?

Again, lights and faulty indicators disappear once the engine is off and reappear after I do a trip of 8-10 miles.

I'm also supposed to be leaving on a European car trip in 4 days... How worrying is this? Please advise and help in any issues you might be aware of!
Thanks!

HDC & YELLOW INDICATORS??? please simplify ?

Also put a location on, there may be some one close who can help