A VAT-compliant invoice (including the VAT and VAT ID number of the retailer) can only be requested from the retailer where you placed your order. Powerpay is the invoicing service provider and does not issue tax-compliant invoices within the meaning of the Value Added Tax Act.
Why is this the case?
VAT-related information (e.g. tax rate, tax amount, VAT ID number) may only be provided by the retailer, as they are considered the service provider. Powerpay only handles the invoicing on behalf of the retailer.