if u are using ghds only once. having your hair cut that often and conditioning well, I can't believe you have split ends. Talk to your hairdresser about strenthening your hair with professional shampoo and conditioning products. Plus, use a heat resisting oil everytime you use the ghds..
I find the Redken products to be fantastic. Cannot be bought in the shops though. Certain hairdressers sell it and you can buy it online. Have a look here www.lookfantastic.com
I saw a special comb advertised on I think it was QVC or maybe Ideal World. You comb it through the hair and it chops off split ends. It was a few months back but they are often readvertised. If you ever watch these shopping channels I only occasionally watch them but they do keep reselling the same products. Blow drying, tying hair up and all cause split ends.