Should friendship be such hardwork?

I have a friend who is really bad at replying to txs, emails- but when shes does they are really long and full of her woes. she has a few personal issues and im happy to give her advice or a hand here and there but i feel like an agony aunt sometimes. i came back from holiday, phoned her and the 1st 10 mins was all about her..! She knows shes bad at replying as we have already had this conversation..what else shall i do?!