I was typing before you put your price on, but I was gonna say Yes, the price is right, you priced it, they said yes, you got the job.
The other guys priced it - they didn't get the job. So they didn't price it right (for this job/customer)
so yours was the right price. For this job/customer.
556/40 = £13.90 pm2 (labour only) = too cheap, maybe
40m2 / 4 days = £139 per day = correct price, maybe
Your about on my level with the last statement