Head scatcher

I have a 1.8m dish in corfu and am trying to get bbc and itv. I set up a mates dish a couple of days ago that was a 1.4m and got it no probs. Cant understand why i cant with 1.8m. i get 90% sig and 90% quality on sly news but when i go to bbc or itv only getting 62%. I have a new invacom 120 lnb. Also just to let you know i use my little eaglebox and mini tv to set up the dishes. i am not a pro but i do set up a lot of dishes for people over here. Help...... please....