I will say, I've had support resolve an issue or two, but I've also had TERRIBLE support from Jagex as well.
A while back, times were tough irl, didn't have the money to re-up my subscription and was on my last week. A friend of mine, being a kind soul and knowing I was in a tough spot, bought me a $25 jagex gift card for membership. Go to redeem it, huh, it gave no options other than runecoins. Strange... so I email jagex. They say, oh, it's because you're a member currently, let your membership drop, then it will work! Following instructions, I let my membership drop without worrying about keeping enough gp for a bond free. Uh oh, same issue, so I email them again. Mind you, the first reply was with 24 hours. This time, I didn't hear back for a week. Over the course of the next week, after finally getting in contact, I was told, confidently and repeatedly, that this would finally solve the problem. Never did I get a reply from the same employee, and it took an additional week for them to figure out it was an issue on their end.
Is 2 weeks of lost p2p the end of the world? Nah, that's why I still play now. It is, however, why I agree with each and every "reddit and Twitter shouldn't be customer support" memes. There is no excuse in this age to have such terrible support for the money they bring in. Hell, outsource it overseas for 10% the cost you'd pay someone local and it'd still be better.