We use a supplement called relax me it's really good stuff
Bailey's calm and condition works well with mine
I do have 3 suggestions.
1. Top Specs Calmex, can buy it in a 3kg tub for about £24 per tub... have used it before on a flighty TB filly and is works wonders it took about 2 weeks before I could see noticeable changes.
2. Dodson and Horrell have a uniquely name supplement named Stroppy Mare it goes for less than £10 per tub, personally I've never had the opportunity to try it out on my mare but I have heard wonderful reviews from fellow competitors.
3. The usual go to which (being ex south African) due to the lack of calming supplements with a colicky anxious older horse and pony was to feed them maize free feed just be careful as ponies are subsepital to laminitis from high protein containing feed so if feeding maize free feed try make sure the protein content is less than 15%.
Hope this is useful and you find it helpful