(Follow Up) Company making me pay for a POS Machine that I did not damage (England)

Here is the link to the original post : https://www.reddit.com/r/LegalAdviceUK/comments/1rg2zkw/company_making_me_pay_for_a_pos_machine_that_i/ .

Since the first post I have read my contract and contacted HR. I found the following in my contract :

NB The Company reserves the right to deduct from your pay the cost of any damage or loss to property or goods, which after a disciplinary hearing was found to have been caused by your negligence or vandalism.

I have also since contacted HR and have asked them to pause the deductions since we never came to any sort of agreement claiming that I was told that the sales manager would get back to me, which he never did, therefore not allowing me any time to provide any evidence. They have replied to me today saying that the deductions will be scheduled to go ahead and that I have to have a "discussion" with the sales manager. I have someone who can vouch who saw the machine and I think the CCTV cameras would have evidence on them aswell.

My question is : Are they allowed to take deductions when nothing was agreed upon and I wasnt able to provide my evidence?

Thank you for your help