MIgrate accounts from Kashflow to Xero

We have 6 years of accounts that we want to migrate to Xero from Kashflow.

We need 770 purchase invoices, with approx four line items per invoice

There are 2800 Bank entries to migrate

There are 90 Journal entries

And approximately 650 sales invoices copying to Xero.

And approximately 140 customers / suppliers.

We need to have the same set of accounts, year ends, etc in xero as we have in Kashflow

We need it doing asap please. Please reply with your experience, method and any questions.

Many Thanks

Jon