"Running late, here's the new ETA" SMS

Write a short SMS to a customer when I'm running late to their job.

Customer first name: {{first_name}}
Original ETA: {{original_eta}}
New ETA (window, not exact): {{new_eta}}
Reason (one line, no excuses): {{reason}}
My first name + business: {{me}}

Write 1-2 short sentences. Acknowledge I'm running late, give the new arrival window, brief reason. Apologise once (not twice). Offer to reschedule if the new window doesn't work.

Return just the SMS body. No greeting like 'Hi' (texts are weird with formal openers).