Hi Suzanne,Welcome to Healing Well! Glad you've joined us.
Using pillows can cause more harm than good. It can bend you in the middle and create more pressure on your stomach, thus causing more reflux. There are wedges that can work, but you'd need a very long, large one to do the job well (extending at least to your waist, as you'll slide down and could get in a bad position again...also it can be hard on your back.)
Here's a description of what to do.
http://my.clevelandclinic.org/disorders/gerd/hic_reflex_care_-_inclining_your_bed.aspx
Here's a link that provides a lot of different bed riser options. I've also used blocks of wood, although bed risers are more stable. You can also put a couple pieces of 4X6 boards cut in squares under the riser if you want to elevate it further. There may be adjustible risers as well.
http://www.amazon.com/Reflux-Relief-Riser-System-Remedy/dp/B0083V6PHA
Here's a UK link that doesn't seem to have as big a selection, but what they have should work. If you scroll down you'll see a wedge pillow. I'm not a fan of this type (I have one) as it can make your back hurt. Some like them, though.
http://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias%3Dkitchen&field-keywords=bed+risers+for+gerd
Hang in there, and good luck!
Denise