An update....
So finally got my flights sorted, it was a bit of an ordeal and took 6 phone calls over three days to sort. They would only let me try a single combination at any one time, so the dates and class I requested were made, had to wait 24 hours to be told no, then go back with another set etc. In the end, the last call I made I got through to someone who turned round and said all the requests were wrong and that he will sort it and he got me the flights I wanted in the class I wanted. So once again it turns out it matters who you speak to... sigh.
Anyway, looking to the positive I have a LHR to KUL to LHR First Class flight booked on the dates I want for £436 and 145K miles! Bargain if you ask me, considering they are going for over £6K for my dates at present on the website and I have a load of VS miles I want to get rid of.
Followed Mark G's advice and called to get the MH reference and sort my seats (1K both ways) as you cannot bring up the flight details on MH website.
So to finalise... It was hard work for me to sort this, but after a lot of headache I got exactly what I wanted. Got to say that the staff in the call centre were helpful throughout, I am just not sure if they knew exactly what they were doing, at least that was the picture I was painted in the final call where it was all sorted.