Great experience with call centres
I started flying Malaysian long-haul about a year ago (between HK and London) and my experiences couldn't be more different. I have called the HK number (if during HK office hours) or the KL number and have never waited more than 5 minutes to be answered. Recent case in point - I booked a trip online at the weekend but the website (which is, admittedly, fairly terrible) got stuck every time I tried to enter seat allocations. I forgot to call them during the day yesterday so missed the HK line but called KL at about 7pm HK time, was through in less than a minute, and had my seat allocations in two minutes. Both times chose English and went through to a fluent English speaker - admittedly I didn't do the Alpha Bravo Charlie thing for the PNR so she got it wrong the first time, but when I switched to Oscar Papa Quebec language there was no problem. Perhaps in future the HK/KL numbers would be a better option? The KL number is 24 hours as well, which is helpful.

But, why do they market connecting flights that they just can't connect to properly?
The thing that has bugged me most about MH is their woeful approach to connecting flights. At certain times there is a very short layover between the incoming London flight to KL and the onward (last) flight to HK. My bags have never made it (which doesn't bother me any more as I have learnt to expect it - it just means they deliver them to my home the next day so I don't have to lug them home, but it is a bore waiting for the bags to (fail to) come through and then have to do the baggage report, particularly when the baggage agent knows they haven't made it but can't be arsed to put a sign up on arrival or at the baggage carousel asking affected pax to go straight to the baggage desk). Twice, however, they haven't got ME on to the connecting flight, which is really annoying. The latter time this happened, someone was waiting for me on arrival to escort me to the new gate. So far, so good, but she walked so slowly I was several times on the verge of saying "if we have this much time, can you please just tell me the gate number and I will get there myself" (I am rather tall and my natural walking pace is quite fast, so it was frustrating for me to have to amble along like that). She spent most of the time calling back and forth on her mobile phone and although I don't understand Bahasa it was fairly clear it wasn't personal, she was liaising with other staff. Long story short, we get to the regional terminal to be told the captain had decided to leave early (...!!). That was REALLY frustrating... They were terribly apologetic, and booked me into the Sama-Sama and got me onto the first flight next day, but you really would think that if they market a connecting flight they would make a bit more effort to make it work.

Still, they are generally a third cheaper than other OW carriers in business class for the flights I use them on, so I will plough on, make sure I have no meetings in the morning of the day I get back, and nothing perishable in my bag!