I think you'll find you're wrong, the illegality is in the fact that I've asked them on more than one occasion to provide an acceptabe VAT invoice and they've failed to do so and that their failure is outside the time allowed to do so.
The information below is copied from HMRC website, however, as I know I'm right in this matter I can't be bothered to look up the exact time period within which the invoice needs to be provided as it's certainly less than five months:
VAT invoices: what they must show
If you are registered for VAT, then whenever you supply goods or services to someone else who is also registered for VAT you must give them a VAT invoice.
What a VAT invoice must show
A VAT invoice must show:
- an invoice number which is unique and follows on from the number of the previous invoice - if you spoil or cancel a serially numbered invoice, you must keep it to show to a VAT officer at your next VAT inspection
- the seller's name or trading name, and address
- the seller's VAT registration number
- the invoice date
- the time of supply (also known as tax point) if this is different from the invoice date - see below
- the customer's name or trading name, and address
- a description sufficient to identify the goods or services supplied to the customer
For each different type of item listed on the invoice, you must show:
- the unit price or rate, excluding VAT
- the quantity of goods or the extent of the services
- the rate of VAT that applies to what's being sold
- the total amount payable, excluding VAT
- the rate of any cash discount
- the total amount of VAT charged
When a VAT invoice must be issued
If you are registered for VAT you must give any VAT-registered customers a VAT invoice for any standard-rated or reduced-rated goods or services you sell them.
If you are a retailer, you do not need to issue a VAT invoice or receipt unless your customer asks for one.
As a VAT-registered supplier, you may be liable to a fine if you do not issue a VAT invoice for a supply you have made when asked to do so by a VAT-registered customer.
There is a time limit within which VAT invoices must be issued – see the section in this guide on time limits for issuing VAT invoices.
Where simplified or modified VAT invoices can be issued Simplified VAT invoices
If you make retail sales and you make a sale of goods or services for £250 or less including VAT, then when a customer asks for a VAT invoice, you can issue a simplified VAT invoice that only needs to show:
- the seller's name and address
- the seller's VAT registration number
- the time of supply (tax point)
- a description of the goods or services
Also, if the supply includes items at different VAT rates then for each different VAT rate, your simplified VAT invoice must also show:
- the total price including VAT
- the VAT rate applicable to the item
If you accept credit cards, then you can create a less detailed invoice by adapting the sales voucher you give the cardholder when you make the sale. It must show the information described in the six bullets above
You do need to keep copies of any less detailed invoices you issue...
Oh and FYI I've been personally VAT registered and the Ltd company I own has for more than a decade so if I'm on the ball, which I am, then I'll know all this stuff, I'm not an employee.
