How to change product values programmatically?

Hi

Thanks for the modules.

Im trying to update the product values through code but keep getting the following error.

PDOException: SQLSTATE[HY000]: General error: 1366 Incorrect integer value: 'entities' for column 'delta' at row 2: INSERT INTO {field_data_field_product} (entity_type, entity_id, revision_id, bundle, delta, language, field_product_product_id)

The actual code I am trying is similar to below

$node->field_product['und']['entities'][0]['form']['commerce_price']['und'][0]['amount'] = $amount;

This is how the structure appears for the product reference fields when creating a product display.

Please could you advise the correct way to alter values through code.

Thank you