Purchases at Bluserena IT with cashback in Italy

Letshop works, but only for small amounts. Where the cashback is a bit more substantial, there are problems. In the case of Bluserena, I purchased a €2,000.00 vacation package and the cashback was not recognized. I sent all the documentation (order, invoice, etc.), including the screenshot confirming that the purchase had been made through Letyshop, and nothing..... Letsyshop also agrees with me, but Bluserena refused the cashback. The "positive" note, so to speak, is that Letyshop still credited me €10.00/one-off for the transaction, having understood that I was right and that the "partner" (Bluserena) had behaved badly. I don't understand why, having situations like this, they don't block the partnership... if the partner, despite having all the documentation, slyly refuses the cashback, I don't understand why Letyshop maintains the partnership...