I've washed hundreds of bungalows and villas over the years and if there's any one thing I've learned in the process, it's that they take a great deal of care in their handling. Filigree, exposed beams under rolled edge verandahs, guillotine sash windows that always leak and more often than not, precious gardens with flowers, topiary or both! The very last thing you want is rough handling of your timber and paint from the 'blasters or scorching of your gardens from the chemical gang.
An immutable reality of washing an old house well and gently is that it takes time. If the quote looks cheap, that's because the operator intends to be in and out quickly. Nobody can be blamed for accepting the cheapest quote - it's intuitive to save money where you can but if you're the owner of an old home that you've either restored, or are in the process of restoring, please be wary of who you contract for the job. I've seen 120 year old kauri filigree that's been blown apart by 2,600psi waterblasters and I've seen magnificent buxus topiary destroyed by caustic soda solution. This will NOT happen on my watch!
Villas and bungalows - proud remnants of our heritage and well worthy of time, care and respect. They are most definitely a GreenAgenda specialty.