Letter to customer after burning plants with chlorine

Customer wrote:

Garrett – Thanks again for coming to clean my house. Question on the cleaners you used and moving plants….seems some of my herbs have taken a turn for the worse. There was a plant by the back door with mint and lemongrass, also close by hanging on the deck were basil and chives. On Thursday all had black edges and look awful, with us not wanting to consume thinking they had cleaner on them. Do you do anything to protect plants? Thinking the mint by the back door didn’t get moved and I should have asked about that prior to you starting.

Photos attached for reference.
Our Response:
Thank you for letting me know. I feel awful that this happened after I was able to help you with your home 🙁
To prevent this from happening, I do take measures to rinse the plants before and after the siding treatment and this generally works without issue the vast majority of the time.But it seems that the plants were no longer wet with water when came back to treat the siding and any overspray had affected them.
The only chemical that is used to clean siding is Chlorine – essentially bleach – and used by nearly every city in the US to treat water and make safe to drink. Chlorine is simply salt water that is electrified and is transformed into bleach. Over time that salt and water separate and bleach naturally breaks down.
There is a good chance that the plants will recover, but what I want to do is to send you a $75 gift card to your garden center of choice to help replace the herbs. So let me know if you’d prefer Stein’s Garden and home, The Home Depot, or your store of choice.
Sincerely,