Modify invoice php-file in Hikashop (Joomla)

Hello I need help to fix a vew php errors. Please see attached image which explains the work ====================================== NOTE: You have to make a protocol of which files were changed! Milestone 100%. ====================================== 1) ADD to product lines a conditioned text. if product has a discount: ---> echo JText::_( 'HIKASHOP_DISCOUNT_TEXT' ); else: --> place nothing 2.) shipping price should be displayed without VAT 3.) Sum of product price of each VAT category should be displayed without VAT 4.) Add shipping price to sum of sum of all products with VAT-ID=2 ____________________________________ This changes should be done urgently. My timezoen: UTC+1 (Western European Summertime) 9:00 - 22:00h Please write the word "Hannes" into your offer so I know that you have read my post eniterly. Thank you!