Unfortunately at the moment it is not possible to receive PVA statements which are older than 6 months as the digital statements are only held online for this timeframe.I would always recommend printing off the digital certificates when they come through to you.
The guidance states:
You’ll only be able to access a statement for 6 months from the date it is published, so you must download and keep a copy of each statement in your records
Please see link below:
Get your postponed import VAT statement
If you don't have access to statements over 6 months old then I would recommend using other import evidence to substantiate your figures on the VAT return.
The digital certificates give the accurate figures for the imports and so in the absence of these it would be best to use the most accurate approximations based on the import evidence that you hold.