Odoo 11 - Front end order limit exceed information in website order confirmation

We have implemented a module in Odoo to limit the total quantity user can have in custody. We are a rental website where customers can rent an amount of products depending on which subscription plan are registered. This implemented module deals with this limitation but this information needs to be shown in frontend ( website).
Right now if customer can't create more orders because limit is exceeded we show a 500 error page.

We should create a page where informing the customer if current order exceeded customer limit or if total open orders exceeded customer limit. I should be able to give following informations:

Hi customer,
Your order exceeds your current plan limit of (xxx€). Please remove some of the limits to be able to proceed.


OR

You exceeded your total credit. You already have jewels for value of (xxx€). Remember that you have to return jewels before making new orders.



Here you can find the module code: https://github.com/avanzosc/odoo-addons
and module description:
Sale Pricelist Limit
This module sets an amount limit in a sale order defined in the pricelist.

Usage
Go to pricelist to add an amount limit.
Bug Tracker
Bugs are tracked on GitHub Issues. In case of trouble, please check there if your issue has already been reported.
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Credits
Images

Contributors

Daniel Campos <danielcampos@avanzosc.es>
Ana Juaristi <anajuaristi@avanzosc.es>
Do not contact contributors directly about support or help with technical issues.