Beka-schreder a week late on delivery, My customer now wants to cancel.

On the 11 of July 2018 an order was placed of a substantial amount of money for street light fittings from Beka-schreder, The agreement was that the goods will be delivered in 4-6 Weeks, The pop for the 50% of the order arrived in their email with a response to say the order has been confirmed on the 17th of July 2018, it is now the 3rd of September 2018 and our goods are not yet ready,t with no light in sight just excuses of delay. the order is now one week delayed and my customer for these products wants to cancel the order. I am a small business and this would be a major setback financially.