Polymorphism and Class Structure for Reporting Solution

I'm coding a report builder in PHP. These reports will either be shown on a web page, emailed or sent through some other communication line. I'd like to support different types of report data (currently text and tabular).

I've built this and it works, the main classes are:

• ReportBuilder
• ReportMailer
• ITextReport
• ITabularReport

My concern is that my solution is not extensible, due to my implementation of ReportBuilder:

public function addTextReport(ITextReport $report)
{
    $this->textReports[] = $report;

    return $this;
}

public function addTabularReport(ITabularReport $report)
{
    $this->tabularReports[] = $report;

    return $this;
}

public function getData()
{
    $data = ['tabularReports' => [], 'textReports' => []];

    foreach($this->tabularReports as $report)
    {
        $data['tabularReports'][] = [
            'title' => $report->getTitle(),
            'keys'  => $report->getDataTitles(),
            'data'  => $report->getData(),
        ];
    }

    foreach($this->textReports as $report)
    {
        $data['textReports'][] = [
            'title' => $report->getTitle(),
            'content'   => $report->getContent(),
        ];
    }

    return $data;
}

My problem:

If I want to add a new report type (say IGraphReport), I need to modify ReportBuilder to accept this new report type, and then parse it in the ReportBuilder::getData method. This violates the Open and Closed principle, and just seems wrong.

Some solutions I considered:

1. Creating a more generic interface IReport, with a render method on it, and replacing the addTextReport and addTabularReport in ReportBuilder to a more generic addReport. However, the different communication channels require different methods of rendering the data so the render method somehow accepts instruction on how to format the data. I'm not sure if this is the cleanest solution.

   2. Letting the communication channel decide on how to render reports, but then I envision a number of if statements checking the type of the report: if($report instanceof ITabularReport) { // handle }, which would then lead me to "replace conditionals with polymorphism" and take me back to point 1.

I'm not sure how to refactor. Any thoughts?