We don’t use pricing levels per customer, so I cannot test this, but you could try the following:
Add “Customer Item Pricing > Customer Item Pricing 1” to the Field Mapping.
Set the Item, Currency and Price Level as normal. Set the Unit Price as “<NULL>” (remember to do this by clicking the pencil icon).
Let us know how you get on.
One other thing to try is when you get to the “Import Options” section, show the Advanced Options and tick “Overwrite Sublists”.
*WARNING* This could really mess up your data if done incorrectly, so I try to avoid it where possible.
If you have a NS Sandbox, I suggest you try this in there first. If you don’t have a sandbox, then try it on one customer only and make sure you import ALL of the current prices for that customer.
The “Overwrite Sublists” option will delete ALL sublist data and replace it with the data in the CSV import. So you must be careful with what you are importing along with these prices.
An example, might be updating one field on another sublist, but if you do not populate ALL of the fields on that sublist, the rest of the values will be wiped.
As far as I understand from NS Help you cannot completely wipe a sublist, so as long as you don’t include any field from a sublist on your CSV import, it will not touch that sublist. For example, if you do not include any Customer Address Sublist fields on the CSV import, it will not touch the Customer Address sublist.
The only other way I can think of is via a custom script, which is quite a bit of work.
Another option you might consider is creating new pricing levels on your items. Then you can assign various customers to various price levels (on the “Financial Tab”. This way you only need to update the price levels on the items (which is likely to be less work than via the customers) For example, if you have 1000 customers and 10,000 SKU, that is 10,000,000 values you need to update on the customer record. Whereas if you had only 100 different price levels (I doubt you would have this many, but let’s assume you did), that’s 1,000,000 (or a 10th) values.
You then don’t need to change the prices for the customer, only change their Price Level on the customer record, which is far easier and much quicker.
Let me know how you get on.