Even if the wall is not by the road front, there should be corner pins. If the lot is rectangular, finding the front pins might help you find a back ones if they aren't buried in the wall. If you find them on your side of the wall, you'll know a little more about your property.

Home advisor always seems overpriced to me--try googling for surveyors in your area if the one who surveyed it last time (when you purchased?) is unavailable. My area also makes surveys available via a FOIL request--maybe the surveyor who did the neighbor's yard will give you a discounted rate. I don't know how accurate this site is, but it suggests half the price you've been quoted so far is the going rate in your area (some of the price depends on property size): https://land-surveyors.promatcher.co...ts-prices.aspx