Lengthening the delivery date at checkout

[Emma100]

Hi

I've a jewellery business where I sell my own jewellery and that of other people. I am using an app called multi vendor marketplace to manage the multi level bit, with some success, though it's not perfect in lots of ways. 

Everything I make is made to order and I currently have a 3 week delivery date which is displayed on each product page. However I am getting emails from customers chasing their orders because the delivery date displayed at checkout says something different and I can't seem to extend it or remove it. 

How do I change the estimated delivery date for my products or even just remove it from the checkout page altogether? It is different for each seller so a blanket change is no good to me, it either needs to reflect what is on each product page from the metafield or removed altogether. 

Can anyone advise me?

Thanks