First of all, you'll want to verify their results. They could be wrong.
Second of all, what are your specifications? If you really guarantee no more than 8.0, didn't you check first before shipping? How do you test?
What else in in your triethylene glycol? Does you supplier need to do a better job of purifying it? Or did your company make it? What do your engineers and chemists say?
The pH of a non-aqueous solution is, at best, a little dicey -- sort of a hit or miss result depending on the method used. At worst, totally invalid, but on some levels this is a personal point of view. At any rate, you may want to titrate to determine exactly how much alkali is there. You'll want a chemist for this, and also to decide how to best neutralize the product and still have it work. Although I'd bet re-purification would work best.