Zara refusing to keep exchange policy

Zara Commercial Warranty of Goods states that as published on counter reads "Zara shall accept exchange of size and/or colour or return of goods within 30 calendar days from purchase date, provided that they have not been used and/or damaged."

In my attempt to exchange a pair of size 4 shoes for size 5 that were purchased on the 22 Sept 2018, Zara Cresta has blatantly refused because I have misplaced my proof of purchase after I have provided my bank statement and the undamaged goods to validate the purchase. From their policy, only the condition of the goods willbe considered for exchange purposes. (The policy only talks about proof of purchase in respect of refund...)

When I escalated the issue to customers Ser vice this was their initial response:

1. Returns and exchanges of an article are allowed within 30 days of the purchase date, provided it has not been used and in the original condition purchased. 2. The amount that was paid will be refunded via the same means used to make the purchase. 3. The original purchase receipt and if used, the credit card and charge slip will be required.

As you can see, their point 1 speaks to my paragraph 1 above Which I am grateful for and in agreement with. (Point 2 & 3 are to be disregarded as they are outside the scope of my transaction). Effectively, I should be allowed to exchange. After I made customer service aware of this, this was their secondary response reflecting a sheer change of policy to create obfuscation:

To clarify the problem with your request – is that all transactions (refund, gift card or exchange) must be done with (1.) a valid receipt which is (2.) within the 30 days.

Does Zara not fully understood their legible and simple policy? Or is justice and real cutomer service a thing of the past?