
Afraid, apart from Laylandii, which is fast growing but would still take at least 5 years to establish enough to look like a 'proper' hedge and stop dogs getting through, there is nothing much you can do. Unless you want to buy Large plants which would cost as much as buying the materials for building a good fence :(
The common hedgings are Privat, both rotundii and wild. Rotundii is the oval leaf that is more domesticated than the wild more spikey leved Privet.
Hawthorn.
Escalonii (But that is more 4-5' max)
Cherry laurel
Cypressus, a bit like laylandii but slower growing, so still 6-8 years to make a hedge.
I am afraid you would be better off proping her fence up and saving up for a fence.
The other option is chain link fencing, and plant a hedge in front that will take up to 10 years to establish.
Sorry for no better news :(
Lea :)